Adverse effects of fluorescent dust marking on the behavior of western black widow spiderlings

Fluorescent dust marking is commonly employed to identify and track small arthropods for studies of ecology, demography, and behavior. Despite its widespread use, no study to date has empirically tested the suitability of dust marking for studies of spider behavior. Here, we test the effects of fluorescent dust marking on proximity of cohabitation, sibling cannibalism, and non‐cannibalistic mortality of western black widow spiderlings, Latrodectus hesperus Chamberlin & Ivie (Araneae: Theridiidae). Results indicate that dust‐marked spiderlings cohabitated at closer proximities and died sooner than undusted spiderlings due to a greater incidence of cannibalism in the dust‐marked group. Thus, we conclude that fluorescent dust marking significantly affected the cohabitation and cannibalistic behavior of L. hesperus spiderlings. Although few studies have reported adverse effects of dust marking on arthropods, our results should serve as a warning to future studies that normal behavior may be disrupted by the use of these fluorescent dust markers. Therefore, preliminary testing should be routine when determining the suitability of any marking technique for not only new species, but also new life stages and behaviors.     

绿地滞尘效应和机理评估进展

绿地滞尘是指大气颗粒物在植物表面的干沉降过程,植物个体特征、绿地结构及环境因素均会对绿地滞尘效应产生影响,模型模拟、实地监测和风洞试验是评估绿地滞尘效应的3种主要方法。现有研究基本上是采用上述方法,从绿地滞尘量或绿地对大气质量的改善作用两方面对城市绿地滞尘效应进行评估,然而评估方法相对单一,影响因素纷繁复杂,评估结果难有定论。为了避免评估方法的滥用和误用,加深对机理的理解,使绿地滞尘研究更好的服务于城市绿地建设,对绿地滞尘效应评估的研究状况进行梳理至关重要。通过仔细分析相关研究的原理及方法发现,绿地滞尘研究多集中在较大尺度上对绿地滞尘量的评估,研究方法虽然一直在更新,且不同方法相互结合已成为趋势,但仍然缺乏大的革新,难以取得较大突破;未来,应加强中小尺度绿地滞尘的研究,深入探讨绿地滞尘机理,在研究方法上寻求创新与突破。     

Spatiotemporal evolution of vortex dust structures in a track plasma

Results are presented from experimental studies of the behavior of dust grains in a track plasma produced by an accelerated proton beam. Dynamic dust structures in such a plasma are obtained for the first time, and their spatiotemporal evolution is thoroughly investigated. The structures develop from a dust spiral, which abruptly transforms with increasing dust density into a differentially rotating dust cloud across which dust-sound waves (including spiral waves generated by the dense central core) propagate. As time elapses, the dust cloud loses its fragments and gradually vanishes. At constant experimental conditions, the lifetime of the structures attains a few minutes.     

Epidemiology of dust-mite-related disease

For many years it has been suggested that allergens derived from the house dust mite played a major role in the pathogenesis of asthma, eczema and some cases of allergic rhinitis. Recently, house dust mite allergens have been purified and specific immunoassays developed with which exposure to house dust mites and their allergens can be more easily determined. Using these tools, epidemiological studies have provided confirmatory evidence that not only is house dust mite exposure associated with the majority of cases of asthma in children and young adults, but that it is causally related to the development of asthma.     

Evaluation of a Low-Cost Electrostatic Dust Fall Collector for Indoor Air Endotoxin Exposure Assessment

Exposure to endotoxin in home environments has become a key issue in asthma and allergy research. Most studies have analyzed floor or mattress dust endotoxin, but its validity as a proxy for airborne exposure is unknown, while active airborne dust sampling is not feasible in large-scale population studies because of logistic and financial limitations. We therefore developed and evaluated a simple passive airborne dust collection method for airborne endotoxin exposure assessment. We explored an electrostatic dust fall collector (EDC), consisting of a 42- by 29.6-cm-sized folder with four electrostatic cloths exposed to the air. The EDC was tested during two 14-day periods in seven nonfarm and nine farm homes and in farm stables. In parallel, active airborne dust sampling was performed with Harvard impactors and floor dust collected by vacuuming, using nylon sampling socks. The endotoxin levels could be measured in all EDC cloth extracts. The levels (in EU/m²) between EDCs used simultaneously or in different sampling periods in the same home correlated strongly (r > 0.8). EDC endotoxin also correlated moderately to strongly (r = 0.6 to 0.8) with the endotoxin measured by active airborne dust sampling and living room floor dust sampling and—in farm homes—with the endotoxin captured by the EDC in stables. In contrast, endotoxin levels measured by floor dust sampling showed only a poor correlation with the levels measured by active airborne dust sampling. We therefore conclude that measuring endotoxin levels with the EDC is a valid measure of average airborne endotoxin exposure, while reproducibility over time is at least equivalent to that of reservoir dust analyses.     

Desert dust impacts on human health: an alarming worldwide reality and a need for studies in West Africa

High desert dust concentrations raise concerns about adverse health effects on human populations. Based on a systematic literature review, this paper aims to learn more about the relationship between desert dust and human health in the world and to analyse the place of West Africa as a study area of interest. Papers focussing on the potential relationship between dust and health and showing quantitative analyses, published between January 1999 and September 2011, were identified using the ISI Web of Knowledge database (N?=?50). A number of adverse health effects, including respiratory, cardiovascular and cardiopulmonary diseases, are associated with dust. This survey highlights obvious dust impacts on human health independently of the study area, health outcomes and method. Moreover, it reveals an imbalance between the areas most exposed to dust and the areas most studied in terms of health effects. None of these studies has been conducted in West Africa, despite the proximity of the Sahara, which produces about half of the yearly global mineral dust. In view of the alarming results in many parts of the world (Asia, Europe, America), this paper concludes by stressing the importance of carrying out impact studies of Saharan dust in West Africa, where dust events are more frequent and intense than anywhere else.     

Charge and potential of a dust grain versus the intergrain distance and establishment of the latter in a low-pressure plasma

Results from experimental studies of ordered dust structures in plasma are reviewed. The experimental conditions and the data on the grain size and intergrain distance in plasma dust crystals are analyzed. It is shown that intergrain distance is a function of the grain size. The range of the ratio of the dust grain size to the Debye radius within which plasma dust crystals can form is determined. A volume cell surrounding a dust grain in plasma is considered. It is found that the potential and charge of the grain depend substantially on the intergrain distance. The charge, potential, and potential energy of a dust grain in a plasma dust crystal, as well as the electrostatic force exerted by the plasma field on the grain, are calculated by the method of molecular dynamics as functions of the intergrain distance. The corresponding analytic approximations and the criterion for the establishment of a steady-state intergrain distance are proposed.     

Dynamics of a high-temperature pinch in the presence of dust

Results are presented from experimental studies of the formation of a pinch in a plasma focus discharge in the presence of Al₂O₃ dust grains. Considerable attention is given to an analysis of the method for creating a dust target and determining its parameters. Phase transitions in a dust medium have been analyzed. It is found that the phase state of the dust component can be substantially affected by the radiation of the imploding plasma shell even in the preimplosion phase of the discharge. It is shown that a pinch produced in the presence of dust is more stable against MHD instabilities.     

Morphological studies of the rat liver after experimental administration of carbon ashes and coal dust

The experiments were carried out in Wistar rats which were given intratracheally samples of carbon ashes or soil dust in the form of the respirable fraction. The morphologic changes and the glycogen content in the experimental animals' livers were evaluated. The content of the trace elements was determined in the applied carbon ashes and soil dust by means of the X-rays diffraction method. The results of the studies show that the morphologic changes in liver depend on the kind of dust and are related to the content of the trace elements and the free silicon dioxide in the carbon ashes and the soil dust.     

Nonlinear screening of dust grains and structurization of dusty plasma: II. formation and stability of dust structures

The second part of the review on dust structures (the first part was published in Plasma Phys. Rep. 39, 515 (2013)) is devoted to experimental and theoretical studies on the stability of structures and their formation from the initially uniform dusty plasma components. The applicability limits of theoretical results and the role played by nonlinearity in the screening of dust grains are considered. The importance of nonlinearity is demonstrated by using numerous laboratory observations of planar clusters and volumetric dust structures. The simplest compact agglomerates of dust grains in the form of stable planar clusters are discussed. The universal character of instability resulting in the structurization of an initially uniform dusty plasma is shown. The fundamental correlations described in the first part of the review, supplemented with effects of dust inertia and dust friction by the neutral gas, are use to analyze structurization instability. The history of the development of theoretical ideas on the physics of the cluster formation for different types of interaction between dust grains is described.     

Effect of dust size distribution on ion-acoustic solitons in dusty plasmas with different dust grains

Theoretical studies are carried out for ion acoustic solitons in multicomponent nonuniform plasma considering the dust size distribution. The Korteweg?de Vries equation for ion acoustic solitons is given by using the reductive perturbation technique. Two special dust size distributions are considered. The dependences of the width and amplitude of solitons on dust size parameters are shown. It is found that the properties of a solitary wave depend on the shape of the size distribution function of dust grains.     

Impacts of dust on plant health,survivorship and plant communities in semi‐arid environments

There is a general perception that dust accumulation on plant surfaces causes negative impacts to plants. Consequently, it is common for environmental regulatory agencies to apply vegetation monitoring requirements to oil, gas and mining developments. We use two independent, medium‐term monitoring studies in semi‐arid Australia to examine this relationship at two scales: plant health and survivorship of a threatened subspecies (Tetratheca paynterae paynterae: Elaeocarpaceae) at Windarling Range between 2003 and 2014; and changes in plant health and floristic composition on Barrow Island between 2009 and 2014. Accumulation of dust decreased rapidly with distance from source. At Windarling Range, even at the site with the highest dust load, there was no significant impact on Tetratheca paynterae paynterae compared with the less dusty sites for 10 years. Similarly, there was no significant effect between distance from the source of dust and floristic composition on Barrow Island for 5 years. The probability of plants transitioning to a lower health condition between one year and the next did not appear to be related to dust load. This is further supported by comparing the same site before and after paving the road (removal of dust source), which showed no clear trends. Trends in plant health are likely to be driven more by the variability of cumulative rainfall in the preceding 5 months than dust load. The observed temporal variation in the mean dust load may also be related to variation in rainfall. In conclusion, in these case studies from semi‐arid Australia, we find no evidence to support the perception that, under the observed climatic condition and dust deposition rates up to 20 or 77 g m^?2 per month at Windarling Range and Barrow Island, respectively, dust accumulation on plants causes negative impacts.     

Coagulation of dust grains in the plasma of an RF discharge in argon

Results are presented from experimental studies of coagulation of dust grains of different sizes injected into a low-temperature plasma of an RF discharge in argon. A theoretical model describing the formation of dust clusters in a low-temperature plasma is developed and applied to interpret the results of experiments on the coagulation of dust grains having large negative charges. The grain size at which coagulation under the given plasma conditions is possible is estimated using the developed theory. The theoretical results are compared with the experimental data.     

Tank bioleaching of copper from combined flotation concentrate and smelter dust

Bioleaching studies were conducted to evaluate the extraction of copper from combined flotation concentrate and smelter dust using two different dust-addition strategies, non-fractional (simultaneously with concentrate) and fractional (step-wise dust addition) in stirred tank reactors. The highest copper extraction obtained with the fractional dust addition was up to 94% while extraction using the non-fractional method leveled off at approximately 44%. Thus, an increased copper recovery of about 50% was achieved with the fractional dust-addition method. It seems that the main reason for increased copper recovery using fractional dust addition could be the control and prevention of chalcopyrite passivation (according to SEM/EDS, XRD, and quantitative mineralogy data). This leads to its improved dissolution.     

Application of PCR-SSCP for molecular epidemiological studies on the exposure of farm children to bacteria in environmental dust

The environmental exposure of farm children to microorganisms in dust has become a focus of interest, since microbial exposure on farms has been related to a reduced prevalence of asthma and atopic diseases in children. Previous studies almost exclusively focused on the determination of microbial counts using conventional culturing or the determination of microbial compounds i.e. endotoxins. In this study PCR-SSCP (single-strand conformation polymorphism) was modified for characterising bacterial communities in environmental dusts and their sensitivity and reproducibility was validated. A fivefold repeated PCR-SSCP analyses of a well homogenised mattress dust, cow-shed dust, swine-shed dust, chicken-shed dust and a horse-shed dust sample, respectively, showed similarities, based on Pearson correlations, ranging from 89.7% to 95.2%. The reproducibility of day to day variations (five days) and gel to gel variations (five gels) was also around 90%. The detection limit of Escherichia coli was 7 x 10(1) cfu g(-1) whereas Listeria monocytogenes and Bacillus licheniformis containing 30% spores showed visible bands at 7 x1 0(2) cfu g(-1). Application of this method to dust samples of 37 sheds and 63 children's mattresses showed that distinct farm environment dusts reflected different SSCP profiles. However, digital analysis of the gels showed that some bands in the profiles of shed- and mattress dusts were found at the same position in the gels. By excision, cloning, sequencing and phylogenetic analyses, these bands were identified as Corynebacterium tuberculostearicum, Corynebacterium mucifaciens, Staphylococcus epidermidis, Acinetobacter lwoffii, Brevibacterium iodinum, Brevibacterium linens and Arthrobacter spp, respectively. These results may reflect transfer of microorganisms from animal sheds to mattresses. In conclusion this study demonstrates that PCR-SSCP is a promising method with sensitive detection limits and moderate sample variances to be applied for epidemiological studies characterizing the exposure of farmers using environmental dust.     

Grain dust and the lungs.

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler''s lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust.     

Dynamics of dust grains in a two-component dusty plasma induced by solar radiation under microgravity conditions

Results are presented from experimental studies of the dynamics of dust grains charged via photoemission under microgravity conditions. The experiments are performed with bronze grains exposed to solar radiation on board the Mir space station. The velocity distribution, temperature, mean charge, and friction and diffusion coefficients of dust grains are determined. An analysis of the data obtained shows that the polarization caused by the separation of opposite charges can significantly affect the transport processes in a two-component dusty plasma consisting of dust grains and the electrons emitted by them.     

Lung Changes in Woodworkers

Pathological changes were observed in the lungs of two workers who had been exposed to wood dust for many years. The cause of death in each case was unrelated to the lung condition. The histopathological changes in the lung were: (1) centrilobular fibrosis and emphysema, (2) the presence of intra-alveolar basophilic particles which had excited a histiocytic and foreign body reaction. Special studies of these bodies tended to confirm the suspicion that they were particles of wood dust. Studies have shown that woodworkers are in an environment heavily saturated with wood dust. The present study suggests that the wood dust is inhaled into the alveoli and may lead to changes in the lungs.     

Dust accumulation in the canopy: A potential cause of dental microwear in primates

Dental microwear researchers consider exogenous grit or dust to be an important cause of microscopic wear on primate teeth. No study to date has examined the accumulation of such abrasives on foods eaten by primates in the forest. This investigation introduces a method to collect dust at various heights in the canopy. Results from dust collection studies conducted at the primate research stations at Ketambe in Indonesia, and Hacienda La Pacifica in Costa Rica indicate that 1) grit collects throughout the canopy in both open country and tropical rain forest environments; and 2) the sizes and concentrations of dust particles accumulated over a fixed period of time differ depending on site location and season of investigation. These results may hold important implications for the interpretation of microwear on primate teeth. © 1995 Wiley-Liss, Inc.     

Use of the indirect rat mast cell degranulation reaction in vitro for characterization of the specific activity of non-infectious allergens]

The test of indirect degranulation of rat mast cells was applied to the study of the specific activity of 16 series of noninfectious allergens from domestic dust (3 series) from hotel dust (7 series) and from the pollen of fescue (6 series). The concentration of protein nitrogen in the allergens from the domestic and hotel dust constituted to 10 000 PNU, and in the allergen from the pollen of fescue--125 000, 50 000, 15 000 and 7 000 PNU. In studying the specific activity of domestic allergens use was made of the sera of patients suffering from bronchial asthma with a marked allergy to domestic dust sera of patients with pollinoses with a marked allergy to fescue pollen was applied to the study of the specific activity of pollen allergen. For the assessment of the indirect degranulation test in mast cells of rats an index of mast cell degranulation of rats (IMCDR) was employed. It was shown that the IMCDR values were equal to 0.46, 0.58, 0.62 in using the domestic dust and in the case of the hotel dust - from 0.17 to 0.28. The mean values for the group of preparations from the domestic dust were 2.5 times greater than for the group of preparations for the hotel dust and were 0.55 and 0.22, respectively. For the allergen from the fescue pollen the IMCDR values varied from 1.23 to 0.16, and increased with the rise of the protein nitrogen concentration (PNU). Additional studies demonstrated that the specific activity of the domestic dust allergen with the crude sera and with those preserved in frozen condition for 3 to 6 months was almost the same. The results obtained permit to draw a conclusion that the method of indirect degranulation of rat mast cells with trizing of commercial batches of infectious allergens.